Function branches 

pub fn branches(
    a: &SurfaceGeometry,
    b: &SurfaceGeometry,
    options: Marching,
    tol: Tolerances,
) -> OgeomResult<Vec<Traced>>

Every branch of the intersection: seed, trace each, and keep the distinct ones.

A branch crossing many sampling cells produces many seeds, and tracing from any of them gives the same curve. So a seed already lying on something traced is dropped rather than followed again, which is what makes the number of branches returned meaningful, and it is the number a boolean will act on.

Errors

OgeomError::Construction if the settings are unusable.